Gaseous fuel burner



NOV. 26, E H RYDEN GASEOUS FUEL. BURNER Filed May 2, 1951 NII 1N VENTORWWK vEPYH; H. RYDEN 'BY :Myw'

ATTORNEYS United GASEOUS FUEL BURNER Application May 2, 1951, Serial No.224,087

12 Claims. (Cl. 158-116) This invention relates to burners for use withnatural, mixed and manufactured gases, and particularly to gas burnersof the type employed in domestic heating, and to gas conversion burnerswhich may be installed in gravity and forced warm air furnaces or hotwater and steam heating boilers originally designed for burning solid orliquid fuels, and provides a single port, self-piloting, flame-retentiontype burner which is unique from the standpoint of its precision andsafety in operation, relative simplicity of construction, ease inmaintenance, and low cost of manufacture.

In the present invention, the burner provides maximum flexibility ofoperation undery varying conditions of air and gas supply. The air-gasmixing and discharge assembly includes a venturi mixing tube wherein thegaseous fuel is mixed with primary air and a coacting burner tube formedwith an upturned extension that terminates in a burner head at the topof the extension, the burner head being of the single port type andhaving approximately the same cross-sectional area of opening as theburner tube passage in order to avoid the devel opment of staticpressure within the tube and burner head during operation.

Heretofore, burners of this type have been used principally for highfuel input rates at elevated pressures wherein the outlet ports in theburner heads are smaller in total cross-sectional area than the fuelinlet, thus producing static pressures within the mixing tube duringoperation of the burner.

While these previous designs are suitable for large capacity burners,they are subject to what is known as flash-back or concussion uponextinction of the flame. In the present invention, a burner head isprovided of the open single port type, which develops little or nostatic pressure and which gives superior fuel burning characteristicsand quiet, non-concussive combustion during all phases of operation atall rates of fuel combustion.

An inherent disadvantage of the single-port type burner has been thefact that the air-gas fuel mixture upon its exit from the head of thetube may possess a higher velocity than that of flame propagation,thereby causing the llame to blow olf or become extinguished, and it isthe major object of the invention to provide a novel burner head thateliminates this difficulty.

An object of this invention is to overcome the abovementioned diicultyby providing a special burner head representing an improvement over theburner disclosed in United States Letters Patent No. 1,978,477 issuedOctober 30, 1934, to G. R. Robertson, and which is particularly welladapted for use in domestic type gas burners.

Another object is to provide a novel, safe, compact, economical gasconversion burner which is comparatively easy to service and maintain.

Further and other objects and advantages will become apparentgas thedisclosure proceeds in conjunction with the appendedclaimsand the.accompanying drawings, in

which;

`atent AO asians Patented Nov. 26, 1957 Figure l is a longitudinalvertical sectional view of the gaseous fuel burner assembly of thisinvention;

Figure 2 is a sectional plan view of the burner head taken along theline 2--2 of Figure l;

Figure 3 is a vertical sectional view of the burner head taken along theline 3-3 of Figure 2.

Referring now in detail to the drawing, the air guide structure includesa housing 10 of generally box like construction formed preferably ofsheet metal and having a front wall 12, a rear wall 14, joined byparallel side walls 16 and parallel top and bottom walls 20 and 22. Thishousing is so formed that the top, rear, and portions of the side wallsare removable as a unit from the remainder of the housing to facilitateservicing of the burner parts therein. The confines of these walls denean air intake chamber 23. Air enters this chamber through an aperture 24which is formed through the front wall 12 near the top thereof and whichextends longitudinally thereacross. Air outlet duct 26 is generallyrectangular in cross section being defined by parallel side walls 28 andparallel top and bottom walls 32 and 34 and is fixed to and extends fromthe front wall 12 of the housing 10. This duct 26 forms a secondarycombustion air passage from the intake chamber 23 to the combustion zonewithin the furnace.

In order to control the amount of air entering the air intake chamber 23through the aperture 24, a shutter or door 36 is pivotally mounted by ahinge 38 on the wall 12 below the aperture 24. A rod 40 is pivotallyconnected at 42 to door 36 and provided at its opposite end with anoutwardly turned extension 44 passing through an elongated slot 46formed through the side wall 16 to be threadedly engaged exteriorly ofWall 16 by a lock nut (not shown).

Rod 40 and the coacting nut provide a means for supporting and fixingshutter 36 in the desired position re1- ative to aperture 24 forcontrolling the quantity of air entering chamber 23.

The formation of this air guide structure embodies certain safetyfeatures which should be noted in particular. As is best shown in Figure2, wall 12 is provided at its top edge with an outwardly extending ange47 which extends completely across the top edge to provide a protectingledge which, when the burner assembly is placed in its operatingposition, abuts against the exterior furnace wall to prevent foreignmaterial from falling into a position to block the air intake aperture24. Further, the construction and mounting of the shutter 36 is suchthat it is normally biased toward its fully open position so that,should the locking means for its support become loosened, it will moveto its open position rather than to its fully closed position, thuseliminating the possibility of shutting off the air supply completely.

Fuel control subassembly The fuel control subassembly includes apressure regulator valve 48 of the diaphragm type and a solenoidactuated gas control valve 50, the outlet port of the former beingconnected to the inlet port of the latter by a suitable conduit. Gaseousfuel is supplied to the inlet port of the pressure regulator valve froma supply conduit through a manually operable main shut-off valve (notshown) to which the inlet port of pressure regulator valve 48 isconnected by a suitable conduit. Gas control valve 50 is of aconventional type having a normally fully closed position and actuableby a solenoid to a fully open position, the energization of the solenoidbeing under control of a conventional room thermostat. The gaseous fuelis conducted from the outlet port of the gas control valve 50 through asuitable conduit, designated generally at 56, which in the disclosedform of the im valve 50 to the primary combustion air and gaseous fuelmixing assembly designated generally as 58.

Primary combustion air and gaseous. fuel mzxngassembly Assembly 58comprises a U-shaped support member 60 having one end wall 61 extrudedas indicated at 62 to form a converging bell shapedthroat for a venturimixing tube generally designated as 63 only the end of the divergingportion 64 of which is shown, As is best shown in Figure 2, the taperedtube forming this diverging portion 6,4 is supported in coaxialalignment with the extruded throat 62, its end being Xed within a recess66 formed in the outer end of the extruded portion 62. The opposite endwallA 67 of support member 60. is provided with an aperture 68 throughwhich is fitted the reduced end portion 69 of a collar 70. Collar 70 isformed with a coaxially aligned bore through which a burner orilice spudholder 74 extends. Spud holder 74 is secured in the bore by a set screw76. Spud holder 74fhas an externally threaded end portion 78- by whichit is connected to the exit endof the conduit 56 leadingfrom gas controlvalve 50. An orifice spud 80.havingla'cylindrical aperture or orifice,formed coaxially therethrough is threaded tightly into the, OPpOSite endof spud holder 74; Sleeve, 84 surrounds spud holder 74, its endextending withinra recess formedwithin the end` of collar 70 in coaxialalignment therewith. Sleeve 84 is fixed within that recess by a setscrew 88. The gas to be y burned emerges from the orifice intoventuritube 63 and primary combustion air, is introduced into the venturi tube63 around the gaseous fuel stream ,as will appear.

Inforder'to control, the lproportion of primary conibustion` air sointroduced, an adjustable air flow control structure is providedwhichhis mounted on the sleeve 84. lathe-.preferred embodiment of thisinvention, this adjustable air flow 'controltstructure comprises shutter90 which is formedwith a radially extending ilange portion 92 andanintegral hub portion.v Shutter 90 is mounted for longitudinalmovementalong the exterior of sleeve84, a set screw 96 being provided forlocking it in adjusted position.

By this construction, gaseous fuel is directed by the orifice spud 80coaxially into the throat of the venturiV mixing Vtube 63 andl primaryair enters the throat of the venturi mixing tube from the air inletchamber, of the housing within which the mixing assembly 58 islocatedrin surrounding `relation to this centrally introduced fuelstream. The primary air stream defined byv flange 92 4and'wall61 is thusan annular air stream surrounding the enteringY fuel charge,and axialadjustmentl of ange 92 controls the effective air intake opening. Thequantity of air passing into the venturi mixing tube is thus determinedby the axial position of the flange prortiong92 of theair shutter 90relative to the extruded venturi throat of the end wal1,61 of thesupport bracket 60. Once the proper position of air shutter 90 has'beendetermined, it is locked in placeon sleeve 84 by set screw 96 and neednot be again disturbed,

It should be noted, that the burner Spud holder 74 may, after looseningset screw 76, be slipped axially from sleeve 84 and collar 70 of themixing assembly without disturbingthe adjustment of the air shutter 90.Due to this construction, when it becomes necessary to clean, adjust orreplace the pressure regulator valve 48, the gas control valve 50 (bothshown in Figures 1 and 2), or the orifice spud 80 (shown in Figure 6),these elements can be removed as a unitary subassembly merely byloosening theset screw.,76, decoupling the conduit 54 from themanuallyoperable shut-otfvalve to which it is connected by.aconventionalunion connection, and removing the connection to one other conduit.

Asis best shown in Figure2, the diverging portion 64 of 4the-venturimixing .tube-63 terminates in a substantiallypylindrical portion 100.` Aconduit or burner tube- 102, which is of substantially constant circularcross section throughout its entire length and which, in the positionshown, closely surrounds the diverging portions 64 and the cylindricalportion 100 of the venturi mixing tube 63, forms an extension thereof ofvariable length for directing the intermixed fuel and air to thecombustion zone within the furnace. Burner tube 102 is supported at oneend by a channel member 104 within which it rests and to which it issecured as by welding and at the other end by a support member 106within the bottom of the tubular air conduit 26. A bolt 108 threadedlyengages a nut 110 welded to the channel member 104 to serve as anadjustable support leg for the forward end of the burner tube.

Burner head and flame deflector The burner tube 102 terminates in anupwardly turned portion indicated at 126 at the end of which is provideda flame retention type burner head assembly 128. The flame retentionburner head of the present invention is, as previously indicated, animproved form of the type disclosed in the aforesaid Robertson patent.As is best shown in Figures 2 and 3, this assembly comprises a collar130 and a spider 132. Collar 130 is essentially cylindrical in crosssection and is provided with a plurality of equally spacedlongitudinally extending depressions or dimples 134 of the same sizeformed inwardly along its outer surface which serve to locate the outerdiameter of the cylindrical spider rim 135 in radially spaced relationwith respect to the inner diameter of the collar to provide asubstantially annular passage consisting of several arcuate passages 136for permitting liow of part of the gas air mixture between the collarand the spider.

The collar 130, as is best shown in Figure 3, has a lower cylindricalportion 131 of reduced cross-sectional area which is press-fitted uponthe end of the burner tube 126. The collar 130 is so positioned relativeto the end of the burner tube 102'by a plurality of studs 138 passingthrough the wall of the collar 130 that an annular opening is formedbetween the bottom edge of the rim 135 and the coaxially aligned upperedge 141 of burnerK tube portion 126, through which opening some of theintermixed gaseous fuel and primary combustion air may pass into thesubstantially annular passage at.136. Since thestuds 138 rest on theedge 141 of burner tube portion 126 and the bottom edge, of thev rim 135rests on-the studs 138, the widthof opening 140 is determined by thediameter of studs 138. By this construction the major portion of theintermixed gaseous fuel and primary combustion air passes through theburner head interiorly of the rim 135 while a smaller portion passesradially through the annular opening 140 and upwardly through thepassages 136. Due to the change in direction of the ow of the gaseousmixture necessary to enter the annular passage at 136, the gases passingtherethrough leave the burner head at a lower velocity than the exitvelocity of the gases of the main jet. The velocity of the gasespassing`through these arcuate passages 136 is sufficiently small so that therate of flame propagation is equal to or greater than the velocity ofthe gases so that the tendency of the flame to blow-off the burner headis eliminated.

A circular deector plate 142 is mounted directly above the exit openingin the burner head. 128 and is suitably formed as shown, to direct thestream of gaseous mixture outwardly toward the walls of the `combustionchamber. The flame deflector 142 is axially fixed upon the upper end ofa support rod 144 which is in turn supported in its vertical positioncoaxially of the burner head 128 by the hub portion 145 of the spider132 of the burner head. The manner in which rod 144 is supported is bestshown in Figure 2. The spider 132 is preferably formed of two similarscroll like members 146 and 148 suitably secured together at 150 and 152as Aby tack welding -and being fonmed of stainless steel strips. Members146 and-148 asians are formed with arcuate portions at 154 and 156respectively which after the members are 4secured together and mountedwithin collar 130 dene a compressed resilient hub or a substantiallycircular opening having resilient walls through which the rod 144extends. Due to the resiliency of the spider structure, the arcuateportions 154 and 156 are pressed against the rod 144 with sutlicientforce to hold it in alignment with the hub portion 145 of the spider.Stops 157 and 158 are attached, as by Welding, to the rod 144 to supportthe flame deector 142 in the desired position above the burner head 128.Stop 157 locates the deector 142 on rod 144, and stop 158 limits thedownward movement of rod 144 into the spider hub.

, Burner ignition assembly 'f This assembly includes a conduit connectedto the vent openings of both the pressure regulator valve 48 and gascontrol valve 50 for discharging any gas escaping from these valvesdirectly into the flame so that it will be burned, the conventionalautomatic pilot connected to the main fuel supply conduit for theignition of the burner, and a runner tube for determining whether thepilot is ignited and for facilitating ignition thereof in the event thatit has become extinguished.

The venting conduit for the pressure regulator valve 48 and the gascontrol valve 50 comprises, as is shown in Figures 1 and 2, a street Tconnector 160 which is threaded into an aperture through the wall of thecontrol chamber side of the pressure regulator 48 which is connectedthrough a duct 162 to the vent aperture of the gas control valve 50, andwhich is connected to one end of a tubular conduit 164 which extendsthrough the air duct 26. Conduit 164 is formed at its opposite end withan upwardly turned portion terminating in an upwardly facing openingadjacent the pilot flame so that any portion of the gaseous fuelcollecting in the vented side of the pressure regulator valve 48 or gascontrol valve 50 will be discharged directly into the ame at the burnerhead and burned rather than discharged into the atmosphere.

The safety pilot assembly is of a generally conventional design,comprising a fully automatic pilot 168 to which gaseous fuel is suppliedfrom the main supply conduit (not shown) through conduit 170, Tconnector 172 and conduit 174. A conventional thermally responsiveelectrical switch mechanism 176 (Figure 1) is mounted adjacent the pilotassembly 168 and is of such construction that so long as the pilot 168is ignited, the switch will be maintained closed and will assume an openposition if the flame of pilot 168 has become extinguished. 'I`he switchof this mechanism is connected by wiring (not shown) in the electricalcontrol circuit of the solenoid of the gas control valve 5t) so that ifthe pilot 168 has become extinguished the solenoid of valve 50 cannotbecome energized to open valve 50 to permit introduction of the gaseousfuel into the burner.

lA runner tube ignition is provided for reigniting the pilot and burnerin the event that its flame has become extinguished. This runner tubeignition comprises a tubular conduit 178 terminating adjacent the pilot168 and connected to a normally closed valve 180 actuate to its openposition by push button 181. The inlet port of valve 180 is connected tothe main fuel supply conduit through T connector 172 and the conduit170. The wall of the tube 178 is pierced with many small slots along itslength to permit escapeof a part of the gaseous fuel introduced therein.In order to determine if the pilot 168 is ignited, itismerely necessaryto open the valve 180. If the pilot is ignitedpthe pilot flame willignite the gas escaping through the slots along the tube 178 back to apoint where the llame becomes visible. 1f the pilot is not ignited, inorder to ignite the pilot it is merely necessary to open the valve 180and hold a lighted match adjacent the valve end of the runner tube 178to ignite the gas escaping through the slot in the wall thereof. Afterthis escaping gas'is once ignited, the flame will pass along the runnertube 17 8 toward the pilot 168 and ignite the pilot.

The three tubular conduits 164, 174 and 178 are connected together andmounted so that they may be readily removed as an assembly for servicingor replacement of the parts thereof. These three tubes are connectedtogether by a bracket 182. In order to support this assembly at itsforward end, a supporting bar or rack 184, which extends substantiallychordally across the arcuate portion of the burner tube 102 and which issuitably secured to the exterior thereof at its opposite ends as bywelding, is provided with a notch 186 which receives a clip 188 which isfixed to the mounting bracket 190 for the thermal responsive switchassembly 176 and the pilot assembly 168. Bracket 190, which is L-shaped,supports the forward end of conduits 178 and 164 in addition tosupporting the thermal responsive switch assembly 176 and the pilotassembly 168.

Referring now to Figure l, the opposite end of this ignition assembly issupported by an L-shaped bracket 192 secured to the Wall 12 of a housing10 at one side of the opening formed by the air duct 26.

The invention may be embodied in other specific forms without departingfrom the spirit or essential characteristics thereof. The presentembodiments are therefore to be considered in all respects asillustrative and not restrictive, the scope of the invention beingindicated by the appended claims rather than by the foregoingdescription, and all changes which come within the meaning and range ofequivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by United States LettersPatent is:

l. In a gaseous fuel burner, in combination with a tube of substantiallyconstant cross-sectional area terminating in an upwardly facing openingand adapted for guiding a gaseous fuel and air mixture to the combustionzone of a furnace, a llame retention burner head secured to said tubeover said opening comprising an outer substantially cylindrical collarhaving an internal diameter slightly larger than that of said tube, aspider having a cylindrical rim portion of substantially the sameinternal diametervas that of said tube, a hollow hub mountedconcentrically on said spider, a flame dellector plate disposed abovesaid burner head and having a support rod mounted in said hub, and meansmounting said spider coaxially Within said collar in such a positionthat the lower edge of the spider rim is axially spaced above the edgeof said tube and the external wall of said spider rim is in concentricspaced relation from the internal wall of said collar, said burner headthus dening a central main opening and a concentric substantiallyannular opening therearound for retardation of a portion of the gaseousmixture passing through said burner head.

2. In a gaseous fuel burner, in combination with a duct of substantiallyconstant cross-sectional area terminating in an upwardly facing openingand adapted for guiding a gaseous fuel and air mixture to the combustionzone of a furnace, a flame retention burner head secured to said ductover said opening comprising an outer substantially cylindrical collarhaving an internal diameter slightly larger than that of said duct,spacer means projecting radially inwardly from said collar over the topof said duct, and a spider mounted coaxially within said collar andhaving a central flame deflector mounting hub and a cylindrical rimportion of substantially the same internal diameter as that of said tubeduct the lower edge of which rests on said spacer means so as to beaxially spaced above the top edge of said duct and the external wall ofwhich is in concentric spaced relation from the internal wall of saidcollar, said burner head thus defining a central main opening and aconcentric substantially annular opening therearound for retardation ofa portion of the gaseous mixture passing through said burner head.

3. In a gaseous fuel burner in combination with a con duit terminatingin an exit port and adapted forV guiding a gaseous'Y fuel andairmixtureto thel combustion zone4 offa'furnace, a burner head mountedon' saidconduit at said' exit port comprising a collar having a portionadapted to'be mounted'on said conduit at said port'and definingl achannel oflarger cross-sectional'area than ysaid conduit, a spiderhaving a rim portion of substantially'the same shape and size as saidconduit and a central'hub coaxial therewith, means for supporting said`spider in axially` spaced relation above the'exit port ofsaid conduitand in'axially spacedrelati'on-within said'collar to define a mainpassage anda peripheral passagetherearound, and a flame deflectormounted on said spider hub'aboveand coaxial withl said passages;

4; Aame-retention-burnerheadadapted to be mountedover the' exit' port ofa conduit'of a gaseous fuel burner for guiding'a gaseous fuel and airmixture to the combustion zone of a furnace comprisinga collar having aportion adaptedto'bemounted on theI conduit at the exit'port anddefining achannel of larger cross-sectional area than that of theconduit, a spider having a rim portion of substantially the same size;shape and thicknessas-thelconduit and a central'hub coaxial therewith,andadapted to support a llame deflector above yand coaxial withtheburnerhead, and means for supporting said spider within said collar so astoibeIV in axially spaced relation'above-'the exit port of the conduitand in coaxially'spaced relation within said collar to divide theAchannel defined by the collar into a main passage and a peripheralpassage therearound.

5. A burner head for a gaseous fuelburner comprising aV gaseousmixtureconducting tube having an upwardly facing end, a collar fixed onsaid tube end and having a section of larger diameter than the tube andextending above the tube end, a tubular member having a downwardlyfacing end, said member. constituting a substantial'continuation of thetube end mounted-within said collar above said tube end and so radiallyspaced inwardly of the collar as to deiinean annular passage with thecollar, at least a portion of said ends of said tube and said memberbeing spaced apart to form passages connecting said annular passage andsaid tube, said annular passage being entirely unobstructed at its upperend and providing a relatively low velocity path for part of the fuelmixture for maintaining combustion of the fuel mixture emerging throughthe said member, and a central ame dellector support socket rigid withsaid tubular member.

6 The burner head defined in claim 5, wherein adjacent-portions of saidtubular member and said collar have icoacting means determining theirradial spacing to define said annular passage.

7. A burner head for gaseous fuel comprising a gaseous mixtureconducting tube having an upwardly facing open end, a collar fixed onthe tube end and having a section of larger diameter than the tubeprojecting above the tube end, and a spider mounted within said collarsection having a rim disposed a short distance above the tube end incoaxial spaced relation with said collar section and a central hub formounting a ame deector, the space between said rim and collar providingan annular fuel mixture passage surrounding the main fuel mixturepassage through the spider.

8. A burner head for gaseous fuel comprising a gaseous mixtureconducting tube having an upwardly facing open end, a collar fixed onthe tube end and having a section of larger diameter than the tubeprojecting above the tube end, a spider having a rim constituting asubstantial continuation of said tubemounted-onl -said 'collar/in'axiallyS spaced'relationabovetheendotsaid tube and4 spaced inwardly ofVlthecollar'so as 'to defineean' annular passagejA therebetweengandmeans providing a' resilientlhub socketL for a' flame'deilectorsupportrod yon said-spiders 9. Aburner'headfor gaseous'fel comprising afgaseousmixture'conducting tube having Aan upwardly facing openJ end, a collarxedon thetube'end' andhaving'asection'- of'larger-diameter thanY theetube projecting above-thel tubeend, a radially compressibleand--expansible ytubularl element mountediwithin'said collarl in axiallyspaced relation to 'the tube" ende; means'ma-intaining said collarandtubular element lin substantially 'coaxially 'lixedlyA spaced'yrelation so as to provide therebetween a substantiallyamnular lowvelocityfe'l mixture' passage; and a hub centrallymounted-onfsaiddtubular element formounting a flame deflecton supportrod. f,

10. Af burner-head@ forgaseousfuel comprising a. gaseous mixture.conducting.;,tube; havingzanr upwardly facing open, end, a collar ixedonthe tube yend and having;afsection1 offlarger'diameter thanthe tubeprojecting? above theftubezend,v a pluralityy of longitudinal ribs in-Tternally of lsaid collar-section,a'plurality.- of spacer ele-v ments onsaid collar extendingjinwardly above the :tube

4 end,v and:a=spiderisurrounded.by said collar having anexpansible:andcontractible rimperipherally spaced from said: collar bysaid ip rojections and having its lower edge restingonsaidpacerelements, Aand a resilient ame rde-V ector. support rodunountinghubcentrally of saidspider.,

11. In thefburnenheaddefned in claim 10, saidhub. being'definedby springarmsnextending inwardly,y from. said 12. A burner head for gaseousfuel'burner comprisingl a gaseous mixture-conducting/tube' having anupwardlyE facingend, a. collar. fixedl onA said tube end and having asection off-larger` diameter than the tube and extending above the` tubeend, a spider having a tubular peripheral portion constituting asubstantial continuation of the tube end mounted vwithin-said collarabove said tube end and so radially spaced inwardly ofthe collar as todefine an annular passage-with the collar, said annular passage being incommunication at its lower end with said tube and entirely unobstructedat its upper end and providing a relatively low velocity path for partof the fuel mixture for maintaining combustion of thefuel mixtureemerging ,through saidfspider, a central ame deflector support socket onsaid spider, and coacting means on said spider and collar fordetermining their radial spacing to define said annular passage.

Referencesf Cited in the le of this patent UNITED STATES PATENTS 892,190Sheppard et al. June 30, 1908 1,919,894V Lorimerv July 25, 19332,130,086 Hart Sept. 13, 1938 2,162,374I Chambers June 13, 19392,178,703! Robbins Nov. 7, 1939 2,183,836 Gordon Dec. 19, 19392,237,889" Rickert` Apr. 8, 1941 2,367,143 Schrader Ian'. 9, 19452,467,626 NormanI Apr.- 19, 1949 2,475,240 Hassmer'et al.' July 5, 19492,537,542 Norman' Jan. 9, 1951 2,541,315 West Feb. 13, 1951 2,541,433Mueller Feb. 13, 1951 2,549,347 Van Tuyl Apr. 17, 1951 2,560,184- NormanJuly 10, 1951

